Resource selection and reselection for direct communications between devices

Abstract

Methods and apparatus for resource allocation in a D2D network (100) are disclosed for reducing resource collisions among wireless devices (200) engaged in device-to-device (D2D) communications. In D2D communications, each wireless device (200) selects a radio resource for signal transmissions and retains the selected resource until a reselection becomes necessary. During the transmission, the wireless device (200) detects a triggering condition for resource reselection. Responsive to the triggering condition, the wireless device (200) performs resource reselection according to a reselection rule that is designed to reduce resource collisions among wireless devices (200).

What is claimed is: 
     
       1. A method of selecting radio resources by a device for use in device-to-device communications with one or more other devices, said method comprising:
 selecting, according to a selection rule, a first radio resource from a shared pool of radio resources for transmission of signals; 
 performing measurements on the first radio resource and one or more candidate radio resources in the shared pool of radio resources; 
 detecting a triggering condition based at least in part on the measurements; and 
 responsive to the detection of the triggering condition, reselecting a second radio resource from the one or more candidate radio resources in the shared pool of radio resources according to a reselection rule, wherein the reselection rule comprises a device-specific pattern, wherein the first radio resource comprises a time resource and a frequency resource, and wherein the device-specific pattern comprises a circular shift of the time resource by a device-specific number of time units. 
 
     
     
       2. The method of  claim 1 , wherein selecting the first radio resource from the shared pool of radio resources for the transmission of signals according to the selection rule comprises selecting a radio resource based on a first utility function. 
     
     
       3. The method of  claim 2 , wherein selecting the first radio resource based on the first utility function comprises selecting said radio resource from the shared pool of radio resources that maximizes the first utility function. 
     
     
       4. The method of  claim 2 , wherein selecting the first radio resource based on the first utility function comprises:
 ranking available radio resources in the shared pool of radio resources based on the first utility function; and 
 selecting one of the available radio resources from among the n highest ranked radio resources. 
 
     
     
       5. The method of  claim 4 , wherein selecting the one of the available radio resources from among the n highest ranked radio resources comprises randomly selecting one of the n highest ranked radio resources. 
     
     
       6. The method of  claim 4 , wherein the one of the available radio resources is selected from among the n highest ranked radio resources according to the device-specific pattern. 
     
     
       7. The method of  claim 1 , wherein the reselection rule is different from the selection rule. 
     
     
       8. The method of  claim 2 , wherein reselecting the second radio resource from the one or more candidate radio resources according to the reselection rule further comprises reselecting the second radio resource based on a second utility function. 
     
     
       9. The method of  claim 8 , wherein reselecting the second radio resource based on the second utility function further comprises reselecting the second radio resource from the shared pool of radio resources that maximizes the second utility function. 
     
     
       10. The method of  claim 8 , wherein reselecting the second radio resource based on the second utility function further comprises:
 ranking available radio resources in the shared pool of radio resources based on the second utility function; and 
 reselecting one of the available radio resources from among the n highest ranked radio resources. 
 
     
     
       11. The method of  claim 10 , wherein reselecting the one of the available radio resources from among the n highest ranked radio resources further comprises randomly selecting one of the n highest ranked radio resources. 
     
     
       12. The method of  claim 10 , wherein the one of the available radio resources is reselected from among the n highest ranked radio resources according to the device-specific pattern. 
     
     
       13. The method of  claim 8 , wherein the first utility function and the second utility function are different. 
     
     
       14. The method of  claim 1 , wherein reselecting the second radio resource from the one or more candidate radio resources according to the reselection rule comprises reselecting the second radio resource according to the device-specific pattern to reduce resource collision between the device and the one or more other devices. 
     
     
       15. The method of  claim 14 , wherein reselecting the second radio resource from the one or more candidate radio resources according to the device-specific pattern further comprises reselecting the second radio resource based on the time resource of the first radio resource and the frequency resource of the first radio resource. 
     
     
       16. The method of  claim 1 , wherein:
 the triggering condition is based on at least one of a utility of the first radio resource and a utility of the second radio resource; and 
 the utility of the first radio resource and the utility of the second radio resource are based on the measurements. 
 
     
     
       17. The method of  claim 16 , wherein the utility of the first radio resource and the utility of the second radio resource are based on respective utility functions that are different. 
     
     
       18. The method of  claim 16 , wherein the triggering condition comprises at least one of the following: the utility of the first radio resource is below a first threshold, and the utility of the second radio resource is above a second threshold. 
     
     
       19. The method of  claim 16 , wherein the triggering condition comprises a difference between the utility of the second radio resource and the utility of the first radio resource exceeding a threshold. 
     
     
       20. The method of  claim 1 , wherein the triggering condition comprises a difference between a first measurement performed on the first radio resource and a second measurement performed on the second radio resource exceeding a threshold. 
     
     
       21. The method of  claim 20 , wherein the first and second measurements comprise interference measurements. 
     
     
       22. The method of  claim 1 , wherein the triggering condition is further based on a time threshold. 
     
     
       23. A device configured for device-to-device communications with one or more other devices, said device comprising:
 an interface circuit operative to transmit and receive radio signals; and 
 a processing circuit operatively coupled to the interface circuit and configured to:
 select a first radio resource from a shared pool of radio resources for transmission of the radio signals according to a selection rule; 
 perform measurements on the first radio resource and one or more candidate radio resources in the shared pool of radio resources; 
 detect a triggering condition based at least in part on the measurements; and 
 responsive to the detection of the triggering condition, reselect a second radio resource from the one or more candidate radio resources in the shared pool of radio resources according to a reselection rule, wherein the reselection rule comprises a device-specific pattern, wherein the first radio resource comprises a time resource and a frequency resource, and wherein the device-specific pattern comprises a circular shift of the time resource by a device-specific number of time units. 
 
 
     
     
       24. The device of  claim 23 , wherein the processing circuit is further configured to select the first radio resource based on a first utility function. 
     
     
       25. The device of  claim 24 , wherein the processing circuit is further configured to select the first radio resource from the shared pool of radio resources that maximizes the first utility function. 
     
     
       26. The device of  claim 24 , wherein the processing circuit is further configured to:
 rank available radio resources in the shared pool of radio resources based on the first utility function; and 
 select one of the available radio resources from among the n highest ranked radio resources. 
 
     
     
       27. The device of  claim 26 , wherein the processing circuit is further configured to randomly select the one of the available radio resources. 
     
     
       28. The device of  claim 26 , wherein the processing circuit is further configured to select the one of the available radio resources from among the n highest ranked radio resources according to the device-specific pattern. 
     
     
       29. The device of  claim 23 , wherein the reselection rule is different from the selection rule. 
     
     
       30. The device of  claim 24 , wherein the processing circuit is further configured to reselect the second radio resource based on a second utility function. 
     
     
       31. The device of  claim 30 , wherein the processing circuit is further configured to reselect the second radio resource from the shared pool of radio resources that maximizes the second utility function. 
     
     
       32. The device of  claim 30 , wherein the processing circuit is further configured to:
 rank available radio resources in the shared pool of radio resources based on the second utility function; and 
 reselect one of the available radio resources from among the n highest ranked radio resources. 
 
     
     
       33. The device of  claim 32 , wherein the processing circuit is further configured to randomly reselect the one of the available radio resources. 
     
     
       34. The device of  claim 33 , wherein the processing circuit is further configured to reselect the one of the available radio resources from among the n highest ranked radio resources according to the device-specific pattern. 
     
     
       35. The device of  claim 30 , wherein the first utility function and the second utility function are different. 
     
     
       36. The device of  claim 23 , wherein the processing circuit is further configured to reselect the second radio resource according to the device-specific pattern to reduce resource collision between the device and the one or more other devices. 
     
     
       37. The device of  claim 36 , wherein the processing circuit is further configured to reselect the second radio resource based on the time resource of the first radio resource and the frequency resource of the first radio resource. 
     
     
       38. The device of  claim 23 , wherein:
 the triggering condition is based on at least one of a utility of the first radio resource and a utility of the second radio resource; and 
 the utility of the first radio resource and the utility of the second radio resource are based on the measurements. 
 
     
     
       39. The device of  claim 38 , wherein the utility of the first radio resource and the utility of the second radio resource are based on respective utility functions that are different. 
     
     
       40. The device of  claim 38 , wherein the triggering condition comprises at least one of: the utility of the first radio resource is below a first threshold, and the utility of the second radio resource is above a second threshold. 
     
     
       41. The device of  claim 38 , wherein the triggering condition comprises a difference between the utility of the second radio resource and the utility of the first radio resource exceeding a threshold. 
     
     
       42. The device of  claim 23 , wherein the triggering condition comprises a difference between a first measurement performed on the first radio resource and a second measurement performed on the second radio resource exceeding a threshold. 
     
     
       43. The device of  claim 42 , wherein the first and second measurements comprise interference measurements. 
     
     
       44. The device of  claim 23 , wherein the triggering condition is further based on a time threshold. 
     
     
       45. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by a processing circuit in a device, configures the device to perform operations corresponding to the method of  claim 1 .